Exam2FlashCards.txt

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Autotroph

An organism capable of developing organic molecules from simple inorganic molecules using either chemical or light energy

Heterotroph

An organism that cannot fix carbon and therefore must obtain organic molecules from other eating organisms

Photosynthesis

a chemical process that converts carbon dioxide and water into organic compounds, especially sugars, using light energy

Respiration

metabolic assimilation of oxygen, accompanied by breakdown of organic compounds, release of energy, and production of carbon dioxide

and water

Net Photosynthesis

photosynthesis – respiration; units are moles CO2 per unit leaf area per unit time

Light Compensation Point

light level (value of PAR) at which photosynthesis and respiration balance each other

Light Saturation Point

light level at which maximum photosynthesis is achieved

Stomata

pores in the leaf or stem of a plant that allow gaseous exchange between the internal tissues and the environment

Water Use Efficiency

ratio of carbon fixed (photosynthesis) per unit of water lost (transpiration); Has important implications for where different types of plants are found

Light reactions

the capture of light energy during photosynthesis; results in the synthesis of ATP (adenosine triphosphate) and NADPH (nicotinamide adenine dinucleotide phosphate)

Dark reactions

the biochemical incorporation of CO2 into simple sugars; do not require the presence of sunlight, but are dependent on the products of the light reactions (ATP and NADPH)

Temperature

a measure of the quantity of thermal energy in an object

Heat

thermal energy in transit from a high-temperature object to a low-temperature object

Radiation

transfer of heat by electromagnetic waves

Conduction

transfer of heat from molecules of one substance to another

Convection

transfer of heat by the movement of a liquid or gas

Evaporation/Condensation

transfer of energy required to initiate phase change from a liquid to a gas or a gas to a liquid

Why are leaves green?

The combination of visible light wavelengths absorbed by the combination of pigments present in the leaf (i.e. chlorophyll) allow for the overall reflection of green light

C3 Photosynthesis

CO2 is captured by rubisco and converted into a three-carbon molecule (phosphoglycerate; 3PGA)

-Rubisco has low affinity for CO2 and favors oxygenation over carboxylation at low CO2 concentrations and warm temperatures

-most common where temperatures are cooler or water availability is high

C4 Photosynthesis

CO2 is captured by PEP carboxylase and converted into a four-carbon acid (oxaloacetate; OAA)

-Unlike rubisco, PEP carboxylase has high affinity for CO2 and does not catalyze photorespiration

-Depends on specialized leaf anatomy; rubisco is found only in cells that are spatially segregated from external air

-favored under warmer and drier conditions

Crassulacean Acid Metabolism (CAM)

uses essentially the same biochemistry as C4 photosynthesis to overcome the limitations of rubisco and eliminate photorespiration

-Instead of using spatial separation, capture of light energy and uptake of CO2 is separated temporally

-most closely associated with highly arid temperate regions

How and why does photosynthetic rate vary with light availability?

The less light, the less photosynthesis. The light level must be above the Light Compensation Point (LCP) for the carbon uptake to exceed the carbon loss in respiration. But it is also possible for photosynthesis to become light saturated, at values of PAR above the Light Saturation Point, whereupon it maxes out. However some plants extremely adapted to shady environments may experience photoinhibition, where overbearing light causes photosynthetic rates to decline as well.

Describe the movement of water between soils, plants, and air and the common mechanism driving this movement

Water moves from larger to smaller values of water potential.

Water loss through transpiration continues as long as (1) the amount of energy striking the leaves is enough to promote evaporation; (2) moisture is available for roots in the soil, and (3) roots are capable of maintaining a more negative water potential than that of the soil.

Water potential (ψ)

the difference in potential energy between pure water (which is defined as having a water potential of zero) and the water in some system, such as in a plant cell or in the soil

Osmotic potential (ψπ)

due to differences in concentration of dissolved solutes (zero or negative)

Pressure potential (ψp)

due to differential hydrostatic or pneumatic pressure in the system (positive or negative)

Matric potential (ψm)

due to the cohesive force that binds water to physical objects (negative)

Gravitational potential (ψm)

due to the pull of gravity on water (negative)

The trade-offs associated with each of the three types of photosynthesis and how climate change might influence global patterns of photosynthesis as a consequence

An organism whose ability to regulate its body temperature is intermediate between an endotherm and an ectotherm. Some small birds and mammals – generally endothermic (‘warm-blooded’) groups – may reduce their metabolic rate during a particular season or even a certain time of day, allowing their body temperature to fall and entering a state of torpor. At the opposite end of the spectrum, certain animals that are generally regarded as ectothermic (‘cold-blooded’) have the ability to generate heat internally for limited periods.

Detritivore

animals that feed on dead plant and animal matter

Torpor

a temporary state of reduced metabolic rate

Nutrient

substance an organism requires for normal growth and activity

Thermoneutral Zone

range of environmental temperatures within which metabolic rates are minimal

Essential Nutrient

a nutrient which cannot be synthesized by a given organisms; must be supplied by the diet

Countercurrent Exchange

an anatomical and physiological arrangement by which exchange of energy or matter takes place between arterial and veneous blood moving in opposite directions

Homeostasis

An organisms regulation of internal conditions such that a balance of said conditions is always maintained within a normal range

Endotherm

organisms who rely on internal (metabolic) heat production to maintain relatively high body temperatures

Relationships between length and surface area or volume are constant as size changes

in isometric scaling whereas in allometric scaling the relationships change.

How surface area/volume ratios change with increasing size of an object and why that might matter for living organisms

When an object increases in size, its surface area increases, however it decreases with respect to volume. This relationship places a critical constraint on the evolution of animals; for example, as most every animal (Loriciferans being exceptions) depends on oxygen to survive, this causes the diffusion of oxygen from the external environment through to the interior tissues to increase in difficulty with an increase in body size. Animals could not get very large at all by way of diffusion alone for oxygen transport. This has allowed for the development of wrinkled surfaces on organisms to increase surface area, and/or elaborate active transport systems for oxygen into the body's interior.

Especially concerned is the relative heat loss which increases with decreasing size for endotherms; this must be offset by increased metabolic activity. Ectotherms have decreasing relative heat gain from their environments with increasing size; therefore large ectotherms are restricted to warmer environments

Herbivory (Digestive)

Developed specialized digestive systems with which they may digest their diets rich in cellulose. Many depend on the presence of microorganisms bacteria/protozoa in their DT for the digestion of cellulose. Some even eat what they regurgitate or defecate for additional digestive purposes.

Grazers feed on

leafy material

Browsers feed on

woody material

Granivores feed on

seeds

Frugivores feed on

fruit

Nectivores feed on

nectar

Carnivory (digestive)

simple stomachs and short intestines; eating animals (herbivores)

Omnivory

feeding on both plants and animals

Detritivory

feeding on dead plant and animal matter

The major pathways through which organisms gain and lose heat

Changes in metabolic rate

Heat exchange

The potential adaptive advantages of acclimatization

How homeothermic ectotherms are able to regulate their body temperature

They might sun themselves when it is cool, seek shade and moisture, and be more still when it is warm

How organismal performance typically relates to temperature and what happens physiologically at extreme temperatures

Poikilotherms respond to increasing temperature with a standard performance curve that increases to a maximum before declining sharply

Cannot be active at extreme temperature

Homeotherms may shiver when cold or sweat when warm.

How width of the thermal neutral zone among species varies with latitude and why

The width of the thermal neutral zone is greater for species closer to the poles due to the fact that they are subjected to much lower temperatures and have evolved such that they maintain their constant metabolic rate over a broader ranger. If Arctic animals were going to shiver in the cold, they wouldn't live in the Arctic!

Trade-offs between endothermy and ectothermy

Endothermy

-Animals can remain active regardless of environmental temperatures

-Energetic demands are very high; limits allocation of resources to growth and reproduction

Ectothermy

-Energetic demands are often low; increases allocation of resources to growth and reproduction

-Animals are often inactive due to environmental temperatures

How a countercurrent exchange system works

An anatomical and physiological arrangement by which exchange of energy or matter takes place between arterial and veneous blood moving in opposite directions, a countercurrent exchange system may work by surrounding cooler veins with warmer arteries in the extremities to warm the blood being returned to the body and minimize heat loss.

Life History

an organism’s lifetime pattern of growth, development, and reproduction

Hermaphrodite (Animal)

an individual that posses both male and female sexual organs (testes and ovaries)

Simultaneous Hermaphrodite

individuals that posses both male and female sexual organs at the same time in its life cycle

Sequential Hermaphrodite:

individuals that change sex at some point during its life cycle

Principle of Allocation

if organisms use energy for one function such as growth, the amount of energy available for other functions is reduced

Mating System

describes the pattern of mating between males and females in a population

Monogamy

males and females form a lasting pair bond, mating with only one member of the opposite sex

Promiscuity

individuals form no pair bond and mate with more than one member of the opposite sex

Polygamy

acquisition by an individual of tow or more mates; a pair bond exists between the individual and each mate

Asexual reproduction

any form of reproduction that does not involve the fusion of gametes

Sexual Selection

differential mating success among individuals as a result of competition for access to mates; male-male combat (intrasexual) and female choice (intersexual)

Parthenogenesis

development of an individual from an egg that did not undergo fertilization

Sexual reproduction

any form of reproduction that involves the fusion of haploid gametes (egg and sperm) into a diploid zygote

Dioecious

plants with male and female reproductive organs on separate individuals

Hermaphrodite (Plant)

plants with both male and female reproductive organs within the same floral structure

Monoecious

plants with male and female reproductive organs in separate floral structures on the same individual